The use of hand-held electronic pipettors is widespread in clinical and research laboratory applications. Electronic pipettors are typically controlled by small microprocessors that are located within in the pipettor housing. The microprocessors are usually programmed through the use of user controls on the pipettor itself. Many electronic pipettors have a small screen display as well. Users can program the pipettor to aspirate a volume of liquid reagent or sample and dispense the aspirated volume or a series of aliquots in successive dispensing operations. Programmable electronic pipettors can also be configured to do more complex operations such as mixing in a pipettor tip, etc.
The electronics industry has seen many advances in recent years. For example, small-scaled LCD displays with improved clarity and enhanced color graphics capabilities, improved processing and memory capabilities, wireless communication devices, etc. are all prevalent. To date, however, it has been difficult to take advantage of many of these advancements in hand-held pipettors. Hand-held electronic pipettors, by their very nature, need to be compact and comfortable in the palm of the hand, yet provide ample room for the motor, the piston and cylinder assembly, and the ejection mechanism, as well as the programmable electronics and a power supply such as a rechargeable battery. An objective of the invention is to provide a configuration for a hand-held electronic pipettor that is able to physically accommodate recent electronic advancements yet meet the above described design requirements.
Another objective of the invention is to provide a hand-held electronic pipettor with improved pipetting accuracy. Pipetting accuracy is especially important when working with small volumes, such as 1 or 2 μl aliquots, however, accuracy can be difficult to attain when pipetting such small aliquots. Difficulties arise not only because of mechanical imprecision of the pipettor components, but also because liquid surface tension issues. Inherently, there are normally differences between forces acting on liquids being aspirated and forces acting on liquids being dispensed, and these differences can cause meaningful inaccuracies when pipetting small volumes.